JPS597205B2 - Phase number conversion transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transformer for converting the number of phases that can easily convert the number of phases from three phases to single phase.

Generally, a three-phase balancing device using a reactor and a capacitor is a circuit that can supply single-phase power from a three-phase circuit without causing three-phase unbalance.

As shown in Figure 1, this circuit connects a capacitor C between V and W, a reactor L between W and U, and supplies single-phase power from between U and V, and a single-phase load P ( KVA) and load power factor Cosφ, the reactor capacity PL (KVA) and capacitor capacity PC (KV
A) is expressed by the following formula. PL■P(Cosφ/ι1+S
lnφ) PC=P(C0sφ/V+slnφ) If the load power factor is cosφ■l, it is said that three-phase balancing can be achieved by preparing a capacitor and reactor with a capacity 1/V times the capacity of a single-phase load. It is something.

FIG. 2 shows a vector diagram of the current in this circuit.
However, as shown in Figure 3, in conventional embodiments that utilize the above principle, a balanced circuit is constructed by transforming the voltage using a three-phase transformer and connecting a capacitor C and a reactor L to the secondary side. Ta. Although the reactor may be installed separately from the transformer, it is usually built into the transformer to reduce the installation area. In either case, the transformer and reactor are manufactured individually and used in combination, and they tend to be large in size and heavy, resulting in expensive phase conversion equipment that is not only difficult to handle but also expensive. There were some flaws that I had no choice but to become. This invention was made to improve the drawbacks of the conventional example described above, and by integrating the transformer and the reactor, the reactor winding and iron core are shared with the transformer, and the body size and weight are small. The present invention provides a transformer for converting the number of phases, which is intended to be lightweight.

Hereinafter, one embodiment of the present invention will be explained in detail with reference to FIGS. 4' to 6.

In FIG. 4, the primary winding of the transformer is a V-connection wound around the U and V phases, and the secondary windings are connected to the three phases in a triangular shape. As shown in Figure 5, the iron core has a gap attached to the leg where the primary winding is wound. A single-phase load is connected between u and a capacitor between u and w.

Further, since a gap is inserted in the iron core of the W-phase leg where the primary winding is not wound, the current necessary to excite this portion flows to the secondary winding W-phase.

This current flows through the U and V phases of the primary winding in order to circulate within the triangular shape of the secondary side.
Phase current flows. By adjusting the gap of the W-phase leg, the excitation impedance of the W-phase changes, so the reactance required for three-phase equilibrium can be set.

Now, if the circulating current 1L, capacitor current 1C, and single-phase load current 1R are adjusted so that IR-V〒IL=V~1C, the following equation holds true. For simplicity, let the turns ratio of the primary and secondary be l: and assume that it is an ideal transformer, then the following equation holds true.

Therefore, as is clear from the vector diagram in FIG. 6, the primary three-phase currents are balanced. As explained in detail above, according to the present invention, a gap is provided in the core leg, and the energy consumption at the gap portion is increased. Since the reactor is operated by ampere turns, the connection on the primary side may be not only a V-connection but also a triangular connection, and the structure of the core may be not only a three-legged core but also a multi-legged core.

Also, a gap is attached to a phase that requires reactance, and there may be many legs with gaps. Therefore, with this invention, a single-phase load can be supplied by integrating a transformer and a reactor and connecting only a capacitor to the outside, which is smaller and lighter than conventional systems, and is less expensive. However, it is possible to obtain a phase number conversion transformer capable of converting three-phase to single-phase at a low cost.

[Brief explanation of the drawing]

Figure 1 is a three-phase balanced circuit diagram using a general capacitor and reactor, Figure 2 is a current vector diagram of Figure 1, and Figure 3 is a three-phase balanced circuit where the voltage is transformed using a conventional transformer on the secondary side. 4 is a connection diagram of a transformer reactor integrated structure according to the present invention, FIG. 5 is an iron core structure according to the present invention, and FIG. 6 is a current vector diagram of FIG. 4. C...Capacitor, L...Reactor, 1...Single-phase load, 2...Transformer, 3
...Primary winding, 4...Secondary winding, 5.
...Gap.

Claims (1)

[Claims] 1. In a transformer that transforms three-phase voltage and outputs single-phase power, the primary winding is wound around two phases, e.g., U phase and V phase, and connected in V, and the secondary winding is wound around two phases, U phase and V phase. A transformer for converting the number of phases, characterized in that the phases are wound and connected in a triangular shape, and a gap is provided in the W-phase core leg where the primary winding is not wound in the tripod core. 2. The phase number conversion transformer according to claim 1, wherein a side leg is attached to the tripod core. 3. The phase number conversion transformer according to claim 1, characterized in that a gap is provided in the side leg attached to the tripod core.